Idiopathic or "functional" urinary incontinence in children--incontinence with no known neurologic or anatomic cause--may take the form of urge incontinence, the most common type of incontinence, which is characterized by detrusor overactivity during the filling phase, or dysfunctional voiding. The latter may be classified as staccato voiding (periodic bursts of pelvic floor activity with prolonged voiding and, in some cases, residual urine), interrupted voiding (insufficient bladder emptying, infrequent voiding with several phases of micturition), or "lazy bladder" syndrome (infrequent voiding and large bladder capacity). The etiology of functional incontinence is unknown. Theories include genetic predisposition, recurrent urinary tract infections, immaturity or too-early toilet training, and sexual abuse. A severe form of urge incontinence, nonneurogenic neurogenic (Hinman) bladder, may be the end stage of dysfunctional voiding, but an occult neurologic component should also be considered. Diagnostic procedures recommended for children with urinary incontinence include careful history taking, a voiding diary, and physical examination to identify symptoms and to minimize the need for invasive procedures. Treatments include behavioral modification, biofeedback, antibiotics, anticholinergics, counseling, and neuromodulation. The antimuscarinics oxybutynin and tolterodine are, at present, the most commonly used drugs to treat incontinence. Common side effects with these agents (ie, reduced saliva production and worsening constipation) can be severe and can cause up to 10% of children using oxybutynin to discontinue treatment. Current evidence suggests that tolterodine may have a more favorable safety profile than oxybutynin. In addition, new antimuscarinics in the pipeline, eg, darifenacin and solifenacin, are expected to possess more favorable safety and tolerability profiles and may therefore help to alleviate these limitations.